*{
    margin:0;
    padding:0;
    list-style: none;
}
img{
    vertical-align: middle;
}
.banner img{
    width:100%;
}

.section1{
    position: relative;
}
.section1 .mainpic{
    width:100%;
    margin-top: 0;
}
.section1 .btn{
    position: absolute;
    bottom:30%;
    left:34%;
}
.section1 .btn:hover{
    transform: rotate(360deg);
    transition: 0.5s;
}
.section2 img{
    width:100%;
}
.section3 img{
    width:100%;
}